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Citrus Aurantium (Bitter Orange Peel)



What is Citrus Aurantium?  Citrus aurantium is a small citrus tree that produces small citrus fruit.  Extracts of the peel of these fruits are now commonly found in many over the counter wait loss products.  The compounds found within Citrus aurantium have adrenergic effects, that is they increase the activity of epinephrine (adrenalin) and norepinephrine (noradrenalin), and therefore have the potential to suppress appetite, increase lipolysis (fat breakdown), but because they are closely related to ephedrene may also carry some health risks (Fugh-Berman and Myers, 2004).


Who Might benefit from Citrus Aurantium?  Citrus aurantium has the potential to aid fat loss, and therefore may be an aid to weight loss. 


Summary of Citrus Aurantium's physiological effects:

  • There's no evidence to support its use as a weight loss supplement

  • May increase blood pressure in hypertensive patients

  • It may increase the toxicity of some commonly used prescriptive medications


What does research say about Citrus Aurantium supplements?  The most active components found within Citrus aurantium fruit are synephrine, which is structurally very similar to adrenalin, and octopamine, which is structurally similar to noradrenalin.  Because they are closely related to ephedrine, they have been included in many weight loss products – despite any real evidence to support their effectiveness.  Many companies now market Citrus aurantium as an alternative to ephedrine, particularly, since ephedrine has been banned both in Europe and the United States.  

To date there is little evidence to support the use of Citrus aurantium for use as a weight loss product (Fugh-Berman and Myers, 2004).  In fact, only one clinical trial (Colker et al., 1999) has looked at the role of Citrus aurantium as an aid to weight loss.  This trial looked at the effect of a combination of 975mg of Citrus aurantium, 528mg of caffeine, and 900mg of St. John’s wort, taken daily for 6 weeks.  The study reported that the treated subjects lost a significant amount of weight (1.4kg) compared with the placebo group, which lost 0.9kg – so there was only a 0.5kg extra loss of weight in the treated group.  In fact, closer inspection of the results, show that there wasn’t a significant difference between the treated group and untreated group (Fugh-Berman and Myers, 2004).   

The increased weight loss in the treated group, albeit only 0.5kg over 6 weeks, cannot be attributed to Citrus aurantium alone.  It is well known that the consumption of around 600mg of caffeine will significantly raise the metabolic rate (Dulloo et al., 1999).  Research has demonstrated that the consumption of 600-1000mg of caffeine, per day, can increase the metabolic rate by around 400kj - approximately 100kcal per day (Dulloo et al., 1989).  This equates to 4200 calories over 6 weeks, enough of an energy increase to burn around 0.5 - 0.6kg of fat – which coincidently is the extra amount of weight lost in the trial group.  If we consider that the dose of caffeine in this trial was close to this range, it is likely that the 528mg of caffeine, used daily in the trial, was responsible for the weight loss in the treated group.  Because of this, there is at present, no evidence to support claims by manufacturers that Citrus aurantium aids weight loss.  In fact, there is no evidence that the Citrus aurantium extracts, synephrine and octopamine, in the levels found in weight loss products would have any fat burning effect on human fat cells (Fugh-Berman and Myers, 2004).     

Consumers should also be made aware that there are still concerns over the safety of Citrus aurantium products (Fugh-Berman and Myers, 2005).  It is well known that synephrine administration can raise blood pressure (Hofstetter et al., 1985).  The consumption of 975mg of Citrus aurantium, appears to be safe for healthy adults (Colker et al., 1999) but may present a risk to people who suffer with hypertension (Fugh-Berman and Myers, 2004).    

A further consideration is that Citrus aurantium may increase the toxicity of some drugs, so anyone on medication should consult their doctor or physician before taking any of these products. 


Is Citrus Aurantium effective?  There is no evidence to support it's use as a weight loss supplement.


How should I take Citrus Aurantium?  At present research does not have any evidence to support the use of Citrus aurantium for weight loss.   



Colker, C. M., Kalman, D. S., Torina, G. C., Perlis, T. and Street, C. (1999) Effects of Citrus aurantium extract, caffeine, and St. John’s Wort on body fat loss, lipid levels, and mood states in overweight healthy adults. Curr Ther Res. 60, 145-153.  

Dulloo, A. G., Geissler, C. A., Horton, T., Collins, A. and Miller, D. S. (1989) Normal caffeine consumption: influence on thermogenesis and daily energy expenditure in lean and post-obese human volunteers. American Journal of Clinical Nutrition. 49, 44-50.  

Dulloo, A. G., Duet, C., Rohrer, D., Girardier, L., Mensi, N., Fathi, M., Chantre, P., Vandermande, J. (1999) Efficiacy of a green tea extract rich in catechin polyphenols and caffeine in increasing 24-h energy expenditure and fat oxidation in humans. Am J Clin Nutr. 70, 1040-1045.  

Fugh-Berman, A. and Myers, A. (2004) Citrus aurantium, an Ingrediant of Dietary Supplements Marketed for Weight Loss: Current Status of Clinical and Basic Research. Exp Biol Med (Maywood). 229(8), 698-704. 

Hofstetter, R., Kreuder, J. and Von Bernuth, G. (1985) The effect of oxedrine on the left ventricle and peripheral vascular resistance. Arzneimittelforschung. 35, 1844-1846.

Although, every attempt is made to ensure the accuracy of the information on this site, the publisher does not accept responsibility for the accuracy of information on this site. This material is not intended for use to diagnose, treat, cure, or prevent any disease.  The publisher does not accept any responsibility for consequences that may arise through the consumption of any supplement or nutritional product discussed on this site. You should always consult a physician, doctor, nurse, pharmacist or health practitioner before consuming any nutritional supplement.  Always read the product label and be aware of any possible side-effects or possible drug interactions before taking any nutritional product.

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Last modified: 01/05/06